I. Field of the Invention
The present invention relates to electronic devices, and more particular to self-cooling stretchable electrical circuits having a conduit forming an electrical component and containing electrically conductive liquid.
II. Description of Related Art
In recent years, a great deal of research and commercial interest has been focused on the area of stretchable electronics, i.e. electronics able to match and deform to surfaces such as human skin or clothing. These systems typically consist of stretchable conductors based on alternative materials, such as thin, wavy traces, conductive polymers, or liquid metals.
Most of the known practical applications have been focused on low power sensing of bioindicators. However, there is an increasing interest in creating higher power systems for computing or embedded actuators in clothing or placed on or near the skin to increase muscle strength or endurance.
One major disadvantage of these applications, however, is that the devices are generally thermally isolated and are typically attached to or in close proximity to the skin of a human. As such, the devices making use of significant amounts of electrical power are impractical while using current technologies in view of the amount of heat generated in operation. Such heat generated by the stretchable electronics can create excessive discomfort for the person wearing the electronics.
There have been previously known stretchable electronics which utilized liquid metal traces to form the electrical component. The electrical component is typically one or more loops forming an electrical inductor. In these devices, fluid channels are filled with liquid metals, such as galinstan (i.e., a common name for an eutectic alloy of gallium, indium and tin) or eutectic gallium indium, to form the conductive material for the inductors. Since millimeter scale cross sections can be achieved without losing the ability to stretch, unlike the wavy traces of other stretchable electronics, the use of fluid channels is particularly well-suited for applications that require very low resistance, such as power applications. However, such power applications necessarily increase the amount of heat generation.